Poland is putting forward its foreign minister, Radoslaw Sikorski, to replace Catherine Ashton as the European Union's foreign policy chief.
Prime Minister Donald Tusk said Sikorski, 51, was a "natural choice" to take over from Ashton, whose five-year term ends in December.
Ashton has ruled out running for a new term.
Sikorski, an outspoken critic of the Kremlin, has played a high-profile role in EU attempts to calm the crisis in Ukraine.
He has called for a more robust European response to Russian military interventions in Georgia and Ukraine.
Other potential candidates include British Foreign Minister William Hague, British Defense Minister Phillip Hammond, and former German Defense Minister Thomas de Maiziere.
The European Council will vote on the appointment in July. It must be confirmed by the European Parliament in September.
Based on reporting by Reuters, AFP, and euractiv.com